I'm about to have our bedroom reskimmed after insulating and plasterboading a bay window and fixing some bits of blown plaster.

1. What is the best way to ensure airtightness at the wall/ceiling joint before skimming? I have cracking here in a few different rooms of my house. Some original lath and plaster ceiling and wet plaster walls, some with an overboarded ceiling.

2. Whats the best way to repair the cracking in the other areas that aren't being reskimmed?

I've seen suggested on here to put mesh tape before plastering but I was wondering about an airtight tape that could be plastered over?

Thanks

I use a vapour barrier on the ceiling and wet plaster it into the wall.

As you can see the cracking I think simply caulking with acrylic sealant/painters caulk would do the trick

Thats great thanks I feel happier having the tape.

Posted By: djhDon't forget to leave a little slack at the wall/ceiling junction so the tape or membrane can accomodate any movement without being torn.

Ok, I guess just enough slack otherwise the corner would be weird to plaster over...

Slightly tardy response here but using the face of plasterboard as AT layer can be improved upon by moving said layer back to the underlying element of assembly. We've used Soudal's geotextile and their LQ AT paint. This paint comes in either blue (which dries black) or white, making application of two layers easy to verify.
Plaster skimmed nicely.

Ah, No. Sorry my entry was misleading. These AT measures were applied to the junction between ceiling plasterboard and the block wall (as yet without plasterboard or wet plaster)